In recent years, cellulose nanocrystals (CNCs) have attracted significant attention not only because of their renewable source and biodegradability but also because of their low density, high aspect ratio, high tensile strength, and unique optical properties.1-3 Also known as nanocrystalline cellulose or cellulose whiskers, CNC particles can be produced from a variety of natural cellulose sources and have dimensions of a few nanometers wide by hundreds of nanometers long. CNCs are generally isolated by acid hydrolysis which removes the amorphous regions of cellulose and leaves behind the highly crystalline regions that are less accessible to acid degradation. Aqueous CNC suspensions can be colloidally stable in water because of surface charged sulfate half ester, carboxylate or phosphate ester groups, depending on the acid hydrolysis method.4 CNCs are now being produced in industrially relevant quantities in both Canada and the USA and are currently being evaluated in a variety of applications including as reinforcing materials in nanocomposites;5 as stabilizers for emulsions and foams;6 and, as components of drilling fluids.7 
Major challenges in using CNCs in commercial products include the ability to disperse the nanoparticles in various materials (both liquids and solids) due to the hydrophilicity of CNCs. Functionalization of the surface of the nanoparticles helps to avoid irreversible agglomeration and aggregation in nonpolar matrices.8 CNCs can be dispersed in nonaqueous media using surfactants or surface chemical grafting through hydroxyl substitution reactions. Use of surfactants is a straightforward method, but a large amount of surfactant is normally required and it has been shown to be rather challenging to disperse modified CNCs in nonpolar solvents like toluene.9 On the other hand, surface chemical grafting, generally involves reactions with the hydroxyl groups on the CNCs surface. Previously reported surface modifications include esterification, sulfonation, oxidation,10 cationization,11 silylation,12 polymer grafting,13 and so on.14 Steric stabilization with surface-grafted polymer brushes has been particularly effective in improving the stability and dispersibility of CNCs in nonpolar solvents and polymer matrices.15 Unfortunately, these reactions are generally performed in organic media where CNCs are unstable and aggregate, and/or are tedious and lengthy processes.16 Therefore, there is a need for a simple, environmentally friendly and low-cost method for producing hydrophobic cellulose nanocrystals (H-CNCs).
Phenols and polyphenols are widely distributed in plant tissues, where they are involved in diverse biological functions such as structural support, pigmentation, chemical defense, and prevention of radiation damage.17 Plant polyphenols display a rich and complex spectrum of physical and chemical properties, leading to broad chemical versatility including adsorption of UV radiation, radical scavenging, and metal ion complexation. The high dihydroxyphenyl (catechol) and trihydroxyphenyl (gallic acid, GA) content of plant polyphenols recently received much attention in the context of nanoparticle surface modification, as catechols are known to strongly bind to surfaces through covalent and noncovalent interactions18 and are prominent constituents of marine polyphenolic protein adhesives.19 The covalent reactions between polyphenol coating on nanoparticle surfaces and nucleophilic groups of polypeptides and other molecules were exploited recently to introduce antifouling functionality.20-21 